The present invention is directed to a high impact catenary conveyor belt support apparatus which is adapted to support a conveyor belt in the load or impact zone, and in particular to a catenary conveyor belt support apparatus which includes two spaced apart support blocks and one or more strings of idler rollers extending between the support blocks whereby the support blocks limit movement of the side edges of the conveyor belt to facilitate sealing of the edges of the conveyor belt against escape of the conveyed material and whereby the support apparatus reduces mistracking of the conveyor belt.
In heavy-duty bulk material conveying applications it is common practice to use catenary idler rollers to support a conveyor belt in the load or impact zone because large impact forces are applied to the belt when the material being loaded is dropped onto the belt. Typical heavy-duty conveying applications include open pit mining conveyors, bucket wheel excavator conveyors, and underground mining conveyors. Typical belt widths range from four feet to twelve feet. Belt speeds range from 500 to 2,000 feet per minute. The tonnage carried by the conveyor belts can be as high as 40,000 tons per hour. The conveyor belts may convey material that includes refrigerator size rocks, clay and logs. The ability of catenary idlers to absorb impact forces is greater than the ability of conventional fixed idler rollers or conventional fixed impact idlers to do so, as catenary idlers are free to move like a string of beads and are often suspended at each end on springs. Catenary support idlers are usually designed for rapid replacement as breakage and damage may occur from exceptionally large impact forces or extreme use.
The primary benefit of a catenary idler is also its main drawback as movement of the idler rollers, which aids in the ability to absorb impact forces, causes the side edges of the belt to move. Movement of the side edges of the conveyor belt by several inches in all directions during loading is common making the load zone of the conveyor impossible to seal such that material being loaded onto the belt spills over the side edges of the belt. Conveyor belts that are subject to heavy impact forces and that are supported by catenary idlers also previously tracked poorly in the load zone because the impact forces are absorbed partially by movement of the idler rollers in an idler string. Movement of the idler rollers can be extreme when large items, such as rocks which may exceed three feet in diameter, strike near the edge of the conveyor belt and push the belt away from the longitudinal center line of the conveyor. Mistracking of the conveyor belt is fostered by idler rollers that become skewed by these impact forces and the tremendous contact pressures that result. There is a great deal of conveyor belt mistracking due to the unstable nature of catenary idler rollers. The present invention provides the impact absorption benefits of a catenary idler apparatus plus the ability to reduce movement of the side edges of the conveyor belt to reduce the escape of fugitive material and the ability to inhibit misalignment of the idler rollers to prevent mistracking of the conveyor belt.
A catenary conveyor belt support apparatus for supporting a conveyor belt having a first edge and a second edge. The conveyor belt support apparatus includes the first support block having a top surface for supporting the conveyor belt at the first edge of the conveyor belt and a second support block having a top surface for supporting the conveyor belt at the second edge of the conveyor belt. The second support block is spaced apart from the first support block. A first idler string includes a first end attached to the first support block and a second end attached to the second support block, such that the first idler string extends between and is attached to the first and second support blocks. The first idler string includes one or more idler rollers for supporting the conveyor belt. The second idler string includes a first end attached to the first support block and a second end attached to the second support block. The second idler string thereby extends between and is attached to the first and second support blocks and is substantially parallel to the first idler string. The second idler string includes one or more idler rollers for supporting the conveyor belt. Each support block includes a support body and first and second shafts extending through the support body. Each end of each support shaft includes a connector member that is located outside of the support body. The connector members are adapted for attachment to the idler strings or to a support structure. The support body may be formed from a single block, from a bottom member and a top member, or from a plurality of slabs located adjacent to one another.
The conveyor belt support apparatus may include one or more restraining assemblies for resiliently connecting an idler string to an anchor member. The restraining assembly includes a coupler member adapted to be attached to an idler string and a resilient biasing member, such as a tether formed from a shock cord, having a first end and a second end. The first end of the biasing member is attached to the coupler member. A connector member is attached to the second end of the biasing member which includes a plurality of attachment points for selectively connecting the connector member to the anchor member. Movement of the idler rollers is restricted by the first and second support blocks and by the restraining assemblies to inhibit misalignment of the idler rollers. The support blocks and restraining assemblies also inhibit movement of the first and second edges of the conveyor belt to reduce the escape of conveyed material from the conveyor belt.